Photopatterned growth of electronically active brush polymers for light emitting diode displays

ABSTRACT

Disclosed herein is a device comprising a substrate; where the substrate comprises a plurality of brush polymers that are covalently or ionically bonded to the substrate; where at least a portion of the brush polymers comprise a covalently bonded emitter moiety.

BACKGROUND

This disclosure relates to photopatterned growth of electronicallyactive brush polymers for light emitting diode displays.

Display devices have become an integral part of society as a means ofinformation transfer. In particular, organic light emitting diode (OLED)displays are among the most energy efficient 2D display technologies andcan be found in everyday appliances, including smartphones, laptops, andtelevisions. Two aspects that have made efficient OLED displays possibleare the use of phosphorescent materials and multi-colored pixel arrays.However, the energy efficiency of OLED displays is offset by the cost ofproduction, in part, due to the use of evaporative deposition processes.Solution-based methods are attractive alternatives that grant access tolow-cost large area and high throughput fabrication (e.g., spin-coating,ink-jet printing, roll-to-roll, and the like), but suffer from limitedpatterning capabilities. Thus, a simple method to generate patternedphosphorescent OLEDs from solution is particularly desirable.

The use of organic and organometallic phosphors have been criticaluseful to OLED device performance as a means to harness energy fromtriplets states, which are electronically generated in a 3:1 ratio withsinglet states. Therefore, while fluorescent materials (singletemitters) are theoretically limited to an internal quantum of efficiency(IQE) of about 60%, phosphorescent materials (triplet emitters) providea theoretical IQE maximum of 100%. The incorporation of heavy transitionmetal ions (e.g., Ir(III), Pt(II), Os(II), Au(III), Ru(II), and Cu(I))in organic complexes has proven to be one of the most effective methodsto generate phosphorescent materials. This is due to their intrinsicallystrong spin-orbit coupling (SOC) that promotes intersystem crossing(ISC), which, when coupled with metal-to-ligand charge-transfer (MLCT),results in the radiative release of triplet energy. Iridium (III)complexes are the most commonly utilized organometallic phosphors inOLEDs due to their impressive photoluminescence quantum yield (PLQY),stability, short triplet state lifetimes, and spectral tunability fromblue to near infrared. Additionally, to suppress inherent concentrationquenching and triplet-triplet annihilation, these complexes are added ashosts and/or emitters into semiconducting host matrices, where covalentattachment to the host mitigates phase separation over time to furtherimprove device longevity.

One popular option for display technology relies on the use of whitelight to render colored images through the use of color filters or colorconversion techniques. In another method, white OLEDs are obtained byblending red, green, and blue emission, using a variety of devicearchitectures and pixel layouts. For example, Samsung has used a PenTileRGBG array of red, green, and blue rectangular pixels to achieve whiteemission for the Nexus One smartphone display. Alternatively, pixelswith a reasonable facsimile of white appearance can be obtained byblending other colors, for example, sky-blue and yellow-orange. Suchpixel patterns layouts are achieved industrially using thermalevaporation of small molecules through a shadow-mask under high vacuum,which is both expensive and time-consuming on large-scale. Althoughresearchers have developed a number of methods to achieve emissivepatterned arrays from solution, including, screen printing, contactlithography, jet printing, and photocrosslinking, practical limitationssuch as fabrication complexity, lack of triplet state emission,scalability issues, and the use of undesirable reagents have preventedcommercialization. For example, printing and contact lithographytechniques require use either complex equipment or numerous iterativeprocessing steps to achieve the desired pattern, while photocrosslinkinghas been used to more rapidly provide fluorescent semiconductingpatterns through step-wise spin-coating/irradiation cycles. However, forphotocrosslinking intense ultraviolet (UV) radiation is often used,along with the use of radical or cationic photoinitiators (e.g.,cyclopentadienyl titanium or iodonium hexafluoroantimonate derivatives),that contaminate the emissive layer (EML) in an OLED device.

It is therefore desirable to have OLED displays that can be manufacturedwithout the use of complex equipment or numerous iterative processingsteps to achieve a desired pattern.

SUMMARY

Disclosed herein is an article comprising a substrate; a first regionhaving a first brush polymer chemically bonded to the substrate; wherethe first brush polymer comprises repeat units of a first ethylenicallyunsaturated monomer and a second ethylenically unsaturated monomer;where the first ethylenically unsaturated monomer comprises a firstelectroactive moiety and where the second ethylenically unsaturatedmonomer comprises a second electroactive moiety that is different fromthe first electroactive moiety; where at least one of the firstelectroactive moiety or the second electroactive moiety is an emittermoiety and where the repeat units of the first ethylenically unsaturatedmonomer are covalently bonded to repeat units of the secondethylenically unsaturated monomer.

Disclosed herein too is a method comprising disposing on a first regionof a functionalized substrate a first composition comprising a firstethylenically unsaturated monomer and/or a second ethylenicallyunsaturated monomer and a solvent; where the first ethylenicallyunsaturated monomer comprises a first electroactive moiety and where thesecond ethylenically unsaturated monomer comprises a secondelectroactive moiety; irradiating the first region with ultravioletradiation and/or visible light; photo-catalyzing the polymerization ofthe first ethylenically unsaturated monomer and the second ethylenicallyunsaturated monomer to form a first brush polymer; and reactivelybonding the brush polymer to the substrate; where the firstelectroactive moiety is different from the second electroactive moietyand where at least one of the first electroactive moiety or the secondelectroactive moiety is an emitter moiety.

Disclosed herein is a device comprising a substrate; where the substratecomprises a plurality of brush polymers that are covalently or ionicallybonded to the substrate; where at least a portion of the brush polymerscomprise a covalently bonded emitter moiety.

BRIEF DESCRIPTION OF THE DRAWING

These and/or other aspects will become apparent and more readilyappreciated from the following description of the exemplary embodiments,taken in conjunction with the accompanying drawings in which:

FIG. 1 depicts a general exemplary reaction scheme that is used inpreparing the light emitting diode display;

FIG. 2 shows the different C^N (MO groups and the graph depicts thecorresponding emitted light of different wavelengths; where C^N refersto a ligand that coordinates through one carbon atom and one nitrogenatom to a metal center. In this case, phenyl pyridine based ligands wereused to coordinate with Ir(III);

FIG. 3A depicts the XPS (X-ray photoelectron spectroscopy) that was usedto determine the chemical composition of the five different films;

FIG. 3B is a graph that shows that the atomic percent of Ir, relative tocarbon, oxygen, and nitrogen, is in good agreement with theoreticalvalues;

FIG. 4A depicts a schematic representation of the method used toreactively bond the brush polymer to the substrate;

FIG. 4B depicts corresponding reflectance and photoluminescence images(step 1—left, and step 2—right);

FIG. 5A shows reflectance (left) and photoluminescence (right) images of2 20×200 μm lines grown for different lengths of time (40 and 60 min.for horizontal and vertical, respectively) and interwoven to providedifferent heights (43, 55, and 85 nm for horizontal, vertical, andintersection, respectively);

FIG. 5B depicts a 3D topographical image of a pattern obtained usingAFM;

FIG. 5C shows correlation between reflectance color and brush thickness;boxed regions are images of sections measured with AFM and regionsbetween are generated color gradients;

FIG. 5D shows reflectance (top) and photoluminescence (bottom) images ofcopolymer brush squares at different time intervals, with 6 mol %IrppyMA used as catalyst/emitter;

FIG. 6A depicts a representation of polymer brushes on ITO and chemicalstructure for poly(M6MA-b-(M6MA-co-IrppyMA));

FIG. 6B depicts a reflectance image showing four distinct regions: 1.ATRP initiator functionalized ITO; 2. poly(M6MA); 3.poly(M6MA-co-IrppyMA); and 4. poly(M6MA-b-(M6MA-co-IrppyMA));

FIG. 6C depicts a photoluminescence image of the image of FIG. 6B;

FIG. 6D shows a SIMS showing overlay of ¹²C ¹⁴N (color) and ¹¹⁵ In¹⁶O(greyscale);

FIG. 7A shows photoluminescence images (λ_(ex)=365 nm) of the three stepRGBG array fabrication, going from red (poly(M6MA-co-IrbtpMA); 500×500μm), to green (poly(M6MA-co-IrppyMA); 125×750 μm), to blue (poly(M6MA);500×750 μm) pixels;

FIG. 7B shows a photoluminescence microscopy image (λ_(ex)=365 nm)showing a magnification of the final pixelated sample (as indicated bythe dotted white box in “FIG. 7A”);

FIG. 7C shows a photoluminescence profile of the pixel array overlaidwith individual red, green, and blue emission profiles;

FIG. 7D depicts CIE 1931 coordinates for the sum emission profile shownas the white trace in “FIG. 7C” along with the individual red,(x,y)=(0.61,0.34), green, (x,y)=(0.32,0.61), and blue,(x,y)=(0.16,0.07), coordinates;

FIG. 8A provides a schematic representation of the multicolored device;

FIG. 8B is an image showing electroluminescence of device under forwardbias;

FIG. 9 is an exemplary schematic of a light emitting diode thatcomprises an emission layer that contains the brush polymers disclosedherein; and

FIG. 10 depicts a reaction scheme for synthesizing ethylenicallyunsaturated monomers comprising a emitter moiety.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments, examples of whichare illustrated in the accompanying drawings, wherein like referencenumerals refer to like elements throughout. In this regard, the presentembodiments may have different forms and should not be construed asbeing limited to the descriptions set forth herein. Accordingly, theembodiments are merely described below, by referring to the figures, toexplain aspects of the present description.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a,” “an,” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. As usedherein, the term “and/or” includes any and all combinations of one ormore of the associated listed items. The term “or” means “and/or.”Expressions such as “at least one of” when preceding a list of elements,modify the entire list of elements and do not modify the individualelements of the list.

It will be understood that, although the terms first, second, third, andso on, may be used herein to describe various elements, components,regions, layers, and/or sections, these elements, components, regions,layers, and/or sections should not be limited by these terms. Theseterms are only used to distinguish one element, component, region,layer, or section from another element, component, region, layer, orsection. Thus, a first element, component, region, layer, or sectiondiscussed below could be termed a second element, component, region,layer, or section without departing from the teachings of the presentembodiments.

It will be further understood that the terms “comprises” and/or“comprising,” or “includes” and/or “including” when used in thisspecification, specify the presence of stated features, regions,integers, steps, operations, elements, and/or components, but do notpreclude the presence or addition of one or more other features,regions, integers, steps, operations, elements, components, and/orgroups thereof.

“About” or “approximately” as used herein is inclusive of the statedvalue and means within an acceptable range of deviation for theparticular value as determined by one of ordinary skill in the art,considering the measurement in question and the error associated withmeasurement of the particular quantity (i.e., the limitations of themeasurement system). For example, “about” can mean within one or morestandard deviations, or within ±30%, 20%, 10%, 5% of the stated value.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art and thepresent disclosure, and will not be interpreted in an idealized oroverly formal sense unless expressly so defined herein.

As used herein, when a definition is not otherwise provided, the term“substituted” refers to a group or compound wherein at least one of thehydrogen atoms thereof is substituted with a halogen atom (F, Cl, Br, orI), a hydroxy group, a nitro group, a cyano group, an amino group, anazido group, an amidino group, a hydrazino group, a hydrazono group, acarbonyl group, a carbamoyl group, a thiol group, an ester group, acarboxylic acid group or a salt thereof, a sulfonic acid group or a saltthereof, a phosphoric acid or a salt thereof, a C1 to C20 alkyl group, aC2 to C20 alkenyl group, a C2 to C20 alkynyl group, a C6 to C30 arylgroup, a C7 to C30 arylalkyl group, a C1 to C30 alkoxy group, a C1 toC20 heteroalkyl group, a C3 to C20 heteroarylalkyl group, a C3 to C30cycloalkyl group, a C3 to C15 cycloalkenyl group, a C6 to C15cycloalkynyl group, a C3 to C30 heterocycloalkyl group, and acombination thereof. Deuterated versions of the aforementioned groupsare also contemplated herein.

As used herein, when a definition is not otherwise provided, the term“hetero” refers to a compound or group including 1 to 4 heteroatomsselected from N, O, S, Se, Te, Si, B, Al, Be and P.

As used herein, when a definition is not otherwise provided, the term“alkyl” group refers to a straight or branched chain saturated aliphatichydrocarbon having the specified number of carbon atoms, and having avalence of at least one, optionally substituted with one or moresubstituents where indicated, provided that the valence of the alkylgroup is not exceeded.

As used herein, when a definition is not otherwise provided, the term“alkenyl” group refers to a straight or branched chain hydrocarbon thatcomprises at least one carbon-carbon double bond, having the specifiednumber of carbon atoms, and having a valence of at least one, optionallysubstituted with one or more substituents where indicated, provided thatthe valence of the alkenyl group is not exceeded.

As used herein, when a definition is not otherwise provided, the term“alkynyl” group refers to a straight or branched chain, monovalenthydrocarbon group having at least one carbon-carbon triple bond, havingthe specified number of carbon atoms, and having a valence of at leastone, optionally substituted with one or more substituents whereindicated, provided that the valence of the alkynyl group is notexceeded.

As used herein, when a definition is not otherwise provided, the alkylgroup, the alkenyl group, or the alkynyl group may be linear orbranched. Examples of the alkyl group may be a methyl group, an ethylgroup, an iso-propyl group, a tert-butyl group, a n-octyl group, an-decyl group, a n-hexadecyl group, and the like. Examples of thealkenyl group may be a vinyl group, an allyl group, a 2-butenyl group,or 3-pentenyl group. Examples of the alkynyl group may be a propargylgroup, or a 3-pentynyl group.

As used herein, when a definition is not otherwise provided, the term“cycloalkyl” group refers to a group that comprises one or moresaturated and/or partially saturated rings in which all ring members arecarbon, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl,cycloheptyl, cyclooctyl, adamantyl and partially saturated variants ofthe foregoing, such as cycloalkenyl groups (e.g., cyclohexenyl) orcycloalkynyl groups, and having a valence of at least one, andoptionally substituted with one or more substituents where indicated,provided that the valence of the alkyl group is not exceeded.

As used herein, when a definition is not otherwise provided, the term“aryl” group refers to a cyclic group in which all ring members arecarbon and at least one ring is aromatic, the group having the specifiednumber of carbon atoms, for example a C6 to C30 aryl group, andspecifically a C6 to C18 aryl group, and having a valence of at leastone, optionally substituted with one or more substituents whereindicated, provided that the valence of the aryl group is not exceeded.More than one ring may be present, and any additional rings may beindependently aromatic, saturated or partially unsaturated, and may befused, pendant, spirocyclic, or a combination thereof.

As used herein, when a definition is not otherwise provided, the term“amino group” refers to —NRR′ wherein R and R′ are independentlyhydrogen, a C1 to C20 alkyl group, or a C6 to C30 aryl group.

As used herein, when a definition is not otherwise provided, the term“siloxane” refers to a compound or polymer and a divalent radical of theformula —[Si(R)(R′)O]— wherein R and R′ are independently hydrogen, asubstituted or unsubstituted C1 to C30 alkyl group, a substituted orunsubstituted C3 to C30 cycloalkyl group, a substituted or unsubstitutedC2 to C30 heterocycloalkyl group, a substituted or unsubstituted C6 toC30 aryl group, a substituted or unsubstituted C3 to C30 heteroarylgroup, a substituted or unsubstituted C2 to C30 alkenyl group, asubstituted or unsubstituted C1 to C30 alkoxy group, or a hydroxy group.

As used herein, the term “hydrogen” or “H” describes the atom containinga single proton, and is inclusive of “deuterium” or “D”.

As used herein, the term “electroactive moiety” describes a chemicalfunctional group which is capable of transporting an electrical chargeand has at least one aromatic ring, preferably two or more aromaticrings, and preferably three or more aromatic rings that are conjugated.In an embodiment, the electroactive moiety comprises a plurality ofaromatic rings that are conjugated. The electrical charge can be eithera positive charge or a negative charge. More specifically, as usedherein, the term “electroactive moiety” describes a chemical functionalgroup capable of transporting an electrical charge at an appliedpotential between −25 volts and +25 volts.

As used herein, the term “emitter” describes a light emitting chemicalfunctional group which is capable of accepting an electron and hole (ifthe recombination directly happens on the emitter) or an exciton (thebound state of a hole and an electron) and emitting a photon through thespontaneous decay of the exciton. Usually the emitter comprises anorganometallic moiety, and more usually comprises an organometalliccomplex. In many cases, the organometallic moiety comprises a heavymetal atom, such as Ir or Pt.

As used herein, the term “host” describes an electroactive chemicalfunctional group which is capable of accepting and transportingelectrons and holes and forming excitons (electron-hole pairs) and thentransferring the exciton to an emitter via Förster and Dexter energytransfer processes. Generally, in order to facilitate Förster transfer,the emission spectrum of the host matrix needs to overlap significantlywith the absorption spectrum of the dopant, whereas efficient Dextertransfer requires the match of energies of the singlet and tripletexcitons on the host with the exciton energies on the emitter group. Insome cases, an offset of the HOMO and LUMO energies between the host andemitter material may be introduced to facilitate direct charge trappingwith phosphorescent emitters. Generally, to achieve efficientelectrophosphorescence some considerations of the host group includepossessing higher triplet energies than those of the emitter groups toprevent reverse energy transfer from the emitter back to the host, aswell as improve confinement of triplet excitons in the emissivematerial; matching the highest occupied molecular orbitals (HOMOs) andthe lowest unoccupied molecular orbitals (LUMOs) of host groups withthose of neighboring charge conduction layers to reduce the hole andelectron injection barriers, thus lowering the device driving voltages;good and balanced charge carrier transport properties for thehole-electron recombination processes; and chemical and thermalstability. Generally, the molecular structure of host usuallyincorporates either hole or electron transport moieties, and in anotherdesign consideration, the host may be bipolar which means the molecularstructure of host incorporates both hole and electron transportmoieties.

The species used to catalyze a photopolymerization may be called aphotocatalyst. In some cases the emitter can also be a photocatalyst.The term photocatalyst describes a chemical functional group thataccelerates the polymerization of ethylenically unsaturated monomerswhile exposed to light. In an embodiment, the photocatalyst may be usedin an amount of 5 mole percent or less based on a total number of molesof the first ethylenically unsaturated moiety and a second ethylenicallyunsaturated moiety.

When a group containing a specified number of carbon atoms issubstituted with any of the groups listed in the preceding paragraph,the number of carbon atoms in the resulting “substituted” group isdefined as the sum of the carbon atoms contained in the original(unsubstituted) group and the carbon atoms (if any) contained in thesubstituent. For example, when the term “substituted C1 to C20 alkyl”refers to a C1 to C20 alkyl group substituted with a C6 to C20 arylgroup, the total number of carbon atoms in the resulting arylsubstituted alkyl group is C7 to C40.

A brush polymer comprises a polymeric chain backbone and has anelectroactive moiety extending radially outwards from the chainbackbone. The electroactive moiety is linked to the chain backbone by acovalent bond, an ionic bond or a hydrogen bond. The chain backbone ofthe brush polymer is covalently or ionically bonded to a substrate. Theelectroactive moiety may be a host material, a hole transport layermaterial (HTL), a hole injection layer material (HIL), an emittermaterial, an electron transport layer (ETL), or the like.

Disclosed herein are color-emitting materials that compriseelectronically active brush polymers (hereinafter “brush polymer) thatare functionalized on a substrate surface. The color-emitting materialsmay be use in a variety of articles (e.g., in displays or in componentsfor displays). The article is photo-patterned to have one or moreregions that emit light of different wavelengths when activated byvisible light. In an embodiment, the article comprises a substrate uponwhich is covalently or ionically bonded an emitting moiety. The emittingmoiety comprises a polymeric backbone to which is covalently bonded anelectroactive moiety. The electroactive moiety functions as an emitter.The emitter is a substituent that is covalently or ionically bonded tothe polymeric backbone to form an electronically active brush polymer.The electroactive moiety may function as a host material, a holetransport layer material (HTL), a hole injection layer material (HIL),an emitter material, an electron transport layer material (ETL), or thelike.

In one embodiment, the brush polymer comprises a homopolymer (that iscovalently or ionically bonded to the substrate) that comprises a firstpolymer that has a first polymer backbone onto which is grafted a firstelectroactive moiety. In an embodiment, the first electroactive moietymay be a host moiety. The homopolymer contains no emitter moiety. Inanother embodiment, the brush polymer comprises a random or blockcopolymer that comprises a first polymer that has a first polymerbackbone onto which is grafted a first electroactive moiety and a secondpolymer covalently bonded to the first polymer) onto which is grafted asecond electroactive moiety. The first electroactive moiety ischemically different from the second electroactive moiety. In anembodiment, the first electroactive moiety and the second electroactivemoiety are different from each other and are selected from the groupconsisting of a host moiety, a hole transport layer moiety (HTL), a holeinjection layer moiety (HIL), an emitter moiety, or an electrontransport layer moiety (ETL). In an exemplary embodiment, at least oneof the first electroactive material or the second electroactive moietycomprises an emitter moiety.

The first polymer is reactively bonded (covalently or ionically bonded)to the substrate. In the block or random copolymer, the firstelectroactive moiety may be a host moiety, while the secondelectroactive moiety is an emitter moiety. In an embodiment, the hostand emitter moieties are randomly distributed along the polymerbackbone.

In an embodiment, the substrate (with the brush polymers reactivelybonded thereto) may be used as on organic light emitting diode. In anembodiment, different regions of the substrate may contain one or moreelectronically active brush polymers that upon activation emit light ofdiffering wavelengths. The resultant light that is visible from thedisplay is the combination of light of different wavelengths emanatingfrom these different regions. In addition to the light emitting block orblocks in the electronically active brush polymer, the polymer may alsocontain one or more blocks that facilitate charge transport andinjection including hole and electron injection. The display comprises afunctionalized substrate to which is covalently or ionically bonded thebrush polymer.

In an embodiment, the display comprises a first region having a firstbrush polymer that emits light of a first wavelength, a second regionhaving a second brush polymer that emits light of a second wavelength, athird region having a third brush polymer that emits light of a thirdwavelength, and so on. The first, second and the third brush polymer areall reactively bonded (covalently bonded or ionically bonded via an endgroup) to the substrate. In an embodiment, the display contains threedifferent regions that emit light of three different wavelengthsrespectively. The display may contain a plurality of these differentregions. In an embodiment, the light emanating from the differentregions combine to produce white light.

In another embodiment, one or more of the first region, the secondregion or the third region may each comprise the first brush polymerthat emits light of a first wavelength, the second brush polymer thatemits light of a second wavelength and/or the third brush polymer thatemits light of a third wavelength. In yet another embodiment, a singleregion on the substrate may comprise the first brush polymer that emitslight of a first wavelength, the second brush polymer that emits lightof a second wavelength and/or the third brush polymer that emits lightof a third wavelength.

In one embodiment, the first brush polymer is a homopolymer thatcomprises a graft that comprises an electroactive moiety, while thesecond brush polymer and the third brush polymer each comprise a randomcopolymer that comprises two or more polymers—a first polymer and asecond polymer each of which contain a graft. Some of the grafts on thesecond brush polymer and the third brush polymer comprise electroactivemoieties that are different from each other (e.g., and can comprise hostmoieties, HTLs, HILs, emitter moieties, or the like). As noted above,one electroactive moiety on the second and/or third brush polymer may ahost moiety while the other may be an emitter moiety.

In an embodiment, the first brush polymer comprises a graft thatfunctions as a host, while the second brush polymer and the third brushpolymer each comprise a random copolymer that comprises two or morepolymers—a first polymer and a second polymer each of which contain agraft. The graft is a pendent moiety that is covalently or ionicallybonded to the polymer chain backbone.

The graft on the first brush polymer functions as a host while the grafton the second brush polymer functions as an emitter. The host and/or theemitter on the second brush polymer and on the third brush polymer aredifferent from one another, which enables them to produce differentcolors. The emitters on the second brush polymer and on the third brushpolymer can interact with the host on the first, second or third brushpolymers.

In short, the electronically active brush polymer comprises either ahost or an emitter-host emissive pair that makes the brush polymersuitable for use in an organic light emitting device. The light emittingdiode display therefore comprises a substrate onto which is disposed(reactively bonded as in covalently bonded and/or ionically bonded) ahost emissive layer and an emitter-host emissive layer. In anembodiment, the emissive layer is formed by a plurality of emitter-hostemissive pairs that are bonded to the backbone of the brush polymer. Inan embodiment, additional layers may be placed on top of theelectroactive brush polymer either through further polymerization orthrough a sublimation process. These layers include a hole-transportlayer (HTL), an electron-transport layer (ETL), an electron injectionlayer (EIL), and a cathode.

These additional layers may also be obtained by grafting onto thepolymer backbone a hole-transport moiety, an electron-transport moietyand/or an electron injection moiety. For example, a hole-transport layermay be produced below the host emissive layer by grafting onto a portionof the respective brush polymer backbones a hole-transport moiety. Thesame polymer backbone may then have grafted onto it a host moiety,followed by a graft that comprises an emitter moiety. This is discussedlater in the section on displays.

Disclosed herein too is a method for manufacturing light emitting diodedisplays that comprise the electronically active brush polymer. Themethod comprises photo-patterning the substrate during the growing ofbrush polymers directly on different regions of the substrate. Thesurface of the different regions of the substrate are functionalizedprior to growing the brush polymers on them. The brush polymers arecovalently bonded or ionically bonded to the substrate. Theelectronically active brush polymers are reacted with an initiatorfunctionalized substrate surface using light thus permitting thedevelopment of emissive layers with three-dimensional patterning. Thistechnology represents a practical and inexpensive method to produceorganic light emitting diode (OLED) displays where the photocatalystused for polymer growth may also serve as an active component in theemissive layer. The main advantage of this method is the spatiotemporalcontrol of the emissive layer, providing access to multiple colors,block copolymer architectures and the potential for displayapplications. This technique can be used to develop layers withdifferent heights. The solution processable OLED device stack has bluecommon layer and its architecture is different from evaporativered-green-blue (RGB) pixels.

In an embodiment, the display comprises a substrate, which has a firstregion having a first brush polymer disposed on the substrate. The firstbrush polymer comprises repeat units of a first ethylenicallyunsaturated monomer and/or a second ethylenically unsaturated monomer;where the first ethylenically unsaturated monomer comprises a firstelectroactive moiety and where the second ethylenically unsaturatedmonomer comprises a second electroactive moiety. It also comprises asecond region having a second brush polymer disposed on the substrate;where the second brush polymer comprises repeat units of a firstethylenically unsaturated monomer and a second ethylenically unsaturatedmonomer; where the first ethylenically unsaturated monomer comprises athird electroactive moiety and where the second ethylenicallyunsaturated monomer comprises a fourth electroactive moiety. The secondethylenically unsaturated monomer is operative to photo-catalyze apolymerization of the first ethylenically unsaturated monomer in thefirst region and in the second region. The first and the secondelectroactive moieties are different from each other and the third andthe fourth electroactive moieties are different from each other.

In an embodiment, the first electroactive moieties and the thirdelectroactive moieties each comprise a host moiety, while the second andfourth electroactive moieties each comprise an emitter moiety.

In an embodiment, a first composition comprising a first ethylenicallyunsaturated monomer and/or a second ethylenically unsaturated monomerand a solvent are disposed on the substrate in a first region. While thefirst region can be irradiated, the other regions (e.g., the secondregion and the third region) are protected from radiation by aphotomask. The substrate is irradiated to trigger a polymerization ofthe first ethylenically unsaturated monomer and/or the secondethylenically unsaturated monomer to form a first brush polymer in thefirst region. In an embodiment, the first brush polymer comprises afirst host and/or a first emitter. Additional blocks may be grown beforeor after the emissive block. These blocks are the result of graftingdifferent moieties onto the backbone of the same graft polymer.

The photomask is then moved exposing a second region (while covering allother regions of the substrate) onto which a second compositioncomprising a first ethylenically unsaturated monomer and/or a secondethylenically unsaturated monomer and a solvent are disposed andirradiated to form the second brush polymer. The second polymercomprises a second host and/or a second emitter. It is to be noted thatthe first ethylenically unsaturated monomer and/or a secondethylenically unsaturated monomer that are disposed on the second regionmay also be referred to as a third ethylenically unsaturated monomerand/or a fourth ethylenically unsaturated monomer. However, for purposesof simplicity, these will continue to be termed the first ethylenicallyunsaturated monomer and/or the second ethylenically unsaturated monomer.Each region will therefore have disposed thereon a first ethylenicallyunsaturated monomer and/or the second ethylenically unsaturated monomereven though these unsaturated monomers may have different chemicalstructures in different regions of the substrate.

During irradiation, the photocatalyst leads to the generation ofradicals which initiates polymerization of the first ethylenicallyunsaturated monomer and/or the second ethylenically unsaturated monomer.This is termed photocatalysis. Photocatalysis is the catalysis of thereaction driven by electromagnetic radiation, preferably by theabsorption of the radiation. The photocatalyst may or may not end upbeing a part of the brush polymer. In an embodiment, the photocatalystdoes not become a part of the brush polymer. Such a photocatalyst mayonly facilitate polymerization of the monomer without becoming a part ofthe brush polymer. Examples of catalysts that facilitate polymerizationwithout being incorporated into the brush polymer include phenothiazineand Ir(ppy)3 {Tris[2-phenylpyridinato-C2,N]iridium(III)}.

It is to be noted that the substrate may comprise a third region, afourth region, and so on, having a third brush polymer and a fourthbrush polymer disposed thereon respectively, where the third brushpolymer contains a third host and a third emitter and the fourth brushpolymer contains a fourth host and a fourth emitter.

In an embodiment, the first region, the second region and/or the thirdregion may comprise a first brush polymer, a second brush polymer and/ora third brush polymer, where each brush polymer has different emittersand/or hosts from the other brush polymers in a given region. In anembodiment, the first region has a first brush polymer disposed on thesubstrate; where the first brush polymer comprises repeat units of afirst ethylenically unsaturated monomer and/or a second ethylenicallyunsaturated monomer; where the first ethylenically unsaturated monomercomprises a first electroactive moiety (e.g., the first host) and wherethe second ethylenically unsaturated monomer comprises a secondelectroactive moiety (e.g., the first emitter). The first region furthercomprises repeat units of a first ethylenically unsaturated monomerand/or a second ethylenically unsaturated monomer; where the firstethylenically unsaturated monomer comprises a third electroactive moiety(e.g., the second host) and where the second ethylenically unsaturatedmonomer comprises a fourth electroactive moiety (e.g., the secondemitter); where the first electroactive moiety is different from thesecond electroactive moiety and where the third electroactive moiety isdifferent from the fourth electroactive moiety.

FIG. 1 depicts a general exemplary reaction scheme that is used inpreparing the light emitting diode display. A substrate 100 comprising asemiconducting or conducting material is first cleaned andfunctionalized with an oligomeric or polymeric moiety 102 that iscapable of being reacted with an ATRP initiator to form an ATRPinitiator functionalized moiety 104. The ATRP initiator functionalizedmoiety 104 is then reacted with a first ethylenically unsaturatedmonomer that contains a first pendent electroactive moiety (e.g., acarbazole moiety) that can function as a host and a second ethylenicallyunsaturated monomer that contains a second pendent electroactive moiety(e.g., an iridium based complex) that can functions as an emitter toform the brush polymer 106.

While the brush polymer 106 shown in the FIG. 1 is a block copolymercomprising two different blocks, the substrate 100 may contain a brushpolymer that has only a single block. As detailed above, the substratemay have different regions that contain different brush polymers. In anembodiment, the substrate may be photo-patterned into a first region108, a second region 110 and a third region 112. Each region containsdifferent brush polymer which enables it to emit light of a differentcolor. Each brush polymer is covalently bonded to the substrate. Thebrush polymers do not contain amino acids.

In the first region 108 (which emits light of a first wavelength), theATRP initiator functionalized moiety 104 is then reacted with a firstethylenically unsaturated monomer that comprises a first electroactivemoiety (e.g., a carbazole moiety) to produce the first brush polymer,while the second region 110 (which emits light of a second wavelength)and the third region 112 (which emits light of a third wavelength) issurface reacted with a first ethylenically unsaturated monomer thatcontains a first electroactive moiety (e.g., a carbazole moiety) asecond electroactive moiety (e.g., an iridium based complex) to producesecond and third brush polymers. The first and the second electroactivemoieties in each of the regions are different from each other. Inaddition, the first electroactive moiety in the second region may be thesame or different from the first electroactive moiety in the thirdregion. The second electroactive moiety in the second region may be thesame or different from the third electroactive moiety in the thirdregion. It is to be noted that (for purposes of identification andsimplicity) the first and second electroactive moieties in the secondregion are referred to as the third electroactive moiety and the fourthelectroactive moiety respectively, and in the third region these arereferred to as the fifth electroactive moiety and the sixthelectroactive moiety respectively. In order to produce light ofdifferent wavelengths from the second region and from the third region,the second brush polymer is chemically different from the third brushpolymer. This will be discussed in detail later.

The substrate can be any suitable electrically conducting orelectrically semiconducting substrate material that is functionalized ina way that a polymer can be grown from or grafted to a surface of thesubstrate. The substrate may be a conventional substrate that is used inan organic light-emitting device, such as glass substrate or atransparent plastic substrate. Examples of substrates include silicondioxide (SiO₂), indium tin oxide (ITO), indium zinc oxide (IZO), tinoxide, zinc oxide, zirconium-doped indium oxide, aluminum-doped indiumoxide, titanium nitride, Ga—In—Sn—O, Zn—In—Sn—O, polystyrenesulfonicacid-doped polyaniline, poly(3,4-ethylenedioxythiophene),poly(thiophene-3-[2[(2-methoxyethoxy)ethoxy]-2,5-diyl) (alsocommercially known as PLEXCORE®) or the like, or a combination thereof.

The substrate is first optionally cleaned to remove any contaminants andto create or expose any reactive species such as hydroxyls, carboxyls,esters, amines, and the like. Examples of cleaning solutions that may beused are piranha solution, nitric acid, sulfuric acid, hydrochloricacid, hydrofluoric acid, and the like. Alternatively, the surface can betreated with a radio-frequency air plasma to clean it and to create orexpose any reactive species present on the substrate.

The cleaned substrate is then functionalized with functional moieties102 capable of undergoing atom transfer radical polymerization (ATRP)with monomers that preferably comprise a monofunctional ethylenicallyunsaturated moiety. In an embodiment, the substrate may befunctionalized with silanes, phosphonic acids/phosphonates, alkenes,carboxylates, catechols, alkynes, amines, thiols, or the like, or acombination thereof.

In an exemplary embodiment, the substrate is first functionalized witholigomeric or polymeric moieties. Examples of oligomeric or polymericmoieties are alkenes having 2 to 40, preferably 3 to 12 carbon atoms.The surface may be functionalized using heat or light. In an embodiment,ultraviolet (UV) light is used to facilitate surface functionalization.

The use of UV light allows for patterning the surface. In an embodiment,the substrate may be spatially and temporally patterned in order toobtain lateral control. By using certain functional moieties, spatialcontrol of the moiety placement can be obtained. Spatial control enablesgrouping the colors into pixels that ultimately can generate displayimages.

For example, using alkenes permits spatial positioning of the functionalgroups on the substrate. Temporal patterning via photo-masking isdiscussed in detail below. The benefit of temporal control is thatmultiple blocks with different compositions can be grown both within asingle brush polymer and within different pixels. Spatial and temporalcontrol is useful for display applications, since multiple colors can begenerated on one substrate, as is the case for red-green-blue pixels ina display.

The functionalized substrate is then reacted with an ATRP initiator toform an ATRP initiator functionalized moiety 104. The substrate 100 withthe ATRP initiator functionalized moiety 104 disposed thereon is termedthe ATRP initiator functionalized substrate. In an embodiment, temporalcontrol via photo-masking may be achieved during the reaction of thefunctional moiety with the ATRP initiator. A photomask is applied to thesubstrate and only on the exposed portion of the substrate is thefunctional moiety reacted with the ATRP initiator.

Examples of ATRP initiators includebis[2-(2′-bromoisobutyryloxy)ethyl]disulfide, 2-azidoethyl2-bromoisobutyrate, bis[2-(2-bromoisobutyryloxy)undecyl] disulfide,2-bromoisobutanoic acid N-hydroxysuccinimide ester, 2-bromoisobutyricanhydride, α-bromoisobutyryl bromide (BIBB),2-(2-bromoisobutyryloxy)ethyl methacrylate, tert-butylα-bromoisobutyrate, 3-butynyl 2-bromoisobutyrate, dipentaerythritolhexakis(2-bromoisobutyrate), dodecyl 2-bromoisobutyrate, ethylα-bromoisobutyrate, ethylene bis(2-bromoisobutyrate), 2-hydroxyethyl2-bromoisobutyrate, 1-(DL-1,2-isopropylideneglyceryl)2-bromoisobutyrate, methyl α-bromoisobutyrate, octadecyl2-bromoisobutyrate, pentaerythritol tetrakis(2-bromoisobutyrate),1-(phthalimidomethyl) 2-bromoisobutyrate, propargyl 2-bromoisobutyrate,1,1,1-tris(2-bromoisobutyryloxymethyl)ethane, 10-undecenyl2-bromoisobutyrate, poly(ethylene glycol) bis(2-bromoisobutyrate) havinga weight average molecular weight of 300 to 5000 grams per mole. Anexemplary ATRP initiator is α-bromoisobutyryl bromide (BIBB).

The ATRP initiator functionalized substrate is then subjected to spatial(also called lateral) temporal patterning. Lateral patterning ispatterning in the plane of the substrate, while spatial control ispatterning that occurs perpendicular to the plane of the substrate.Spatial control may be obtained by using masks with different regionsizes, different filters, or the like, while temporal control (alsoknown as time dependent control) is obtained by varying the intensity orfrequency of radiation, by varying the ratio and the chemistry of themonomers fed to the reactive substrate.

In an embodiment, lateral and temporal control may be accomplished byphotomasking. Photomasking is conducted during the formation of thebrush polymer or prior to the formation of the brush polymer. The use ofa photomask permits the use of different ratios of the secondelectroactive moiety (e.g., the emitter) to the first electroactivemoiety (e.g., the host) in different regions of the substrate duringpolymerization thus producing brush polymers with differentstoichiometric ratios of emitter to host in the different regions. Thedifferent ratios of the emitter to host in the polymer brush areachieved by using differing amounts of the first and secondethylenically unsaturated monomers in different regions. For example, afirst region on the substrate has disposed on it a first ratio of thefirst ethylenically unsaturated monomer to that of the secondethylenically unsaturated monomer. The first region is exposed tovisible light (while all other regions are masked during the exposure)so that the ethylenically unsaturated monomers undergo polymerization.The regions that are covered by the photomask are not affected by theexposure to light during the polymerization. A second region having asecond ratio (different from the first ratio) of the first ethylenicallyunsaturated monomer to that of the second ethylenically unsaturatedmonomer is then exposed to light while all other regions of thesubstrate are masked. The ethylenically unsaturated monomers in thesecond region undergo polymerization. The first ethylenicallyunsaturated monomer that comprises the host undergoes polymerization toform the first block polymer, while the second ethylenically unsaturatedmonomer that contains the emitter undergoes polymerization to form thesecond block polymer. The different regions (having differing ratios ofhost to emitter) emit light of different wavelengths when activated.

In an embodiment, different host and emitter moieties can be used ineach region. By varying the chemistry of the host and emitter moieties,the light emitted in different regions of the substrate may be ofdifferent wavelengths. It is also to be noted that a substrate washingstep with a solvent is preferred between successive polymerizationsteps. In an embodiment, the polymeric endgroups (e.g., halogens such asbromine) may be removed using a photochemical reaction with spatialspecificity at any point during the polymerization process (detailedabove) or non-selectively after the last polymerization is done using achemical reaction.

The first region, the second region and the third regions can have areaswith various cross-sectional geometries when viewed from the top. Thecross-sectional areas can be square, rectangular, circular, triangular,polygonal, or a combination thereof. The first region, the secondregion, the third region, and so on can be periodically arranged oraperiodically arranged. In an embodiment, an average periodicity betweenthe first region and the second region, between the second region andthe third region or between the second region and the third region maybe 10 nanometers or larger, preferably 20 nanometers to 10 micrometers,and more preferably 250 nanometers to 5 micrometers.

In another embodiment, surface grown polymer brush heights can be from 5to 800 nm, more preferably from 10 to 600 nm.

The monofunctional ethylenically unsaturated moieties have a host andemitter functional groups bonded thereto. In an embodiment, themonofunctional ethylenically unsaturated moiety may comprise vinylaromatic monomers, acrylates, methacrylates, vinyl ethers, maleates,fumarates, acrylamides, styrenics, cyanoacrylates, or the like, or acombination thereof.

The host is a pendent group (and can be viewed as a first graft) that iscovalently or ionically bonded to the chain backbone of the first blockpolymer. The emitter is also a pendent group (and can be viewed as asecond graft) that is covalently or ionically bonded to the chainbackbone of the second block polymer. The first block polymer and thesecond block polymer are covalently bonded to each other to form arandom or block copolymer (which is also referred to herein as the brushpolymer).

It is generally desirable for the first excited triplet state (T1) ofthe host to be preferably higher than the first excited triplet state ofthe emitter. In a fluorescent system, the first excited singlet state ofthe host is normally higher than the first excited singlet state of theemitter. Emitter-host systems where the emitter emitters have arelatively short wavelength, such as in the blue region (shorter than500 nm) meet the aforementioned criteria. As used herein, a“phosphorescent system” is an emissive system in which most of theemission intensity is due to transitions from a triplet state, and doesnot entirely exclude some fluorescent emission. A “fluorescent system”is an emissive system in which most of the intensity is due totransitions from a singlet state. A thermally activated delayedfluorescent system (TADF) is an emissive system where a portion ofexcitons in the excited triplet state of the emitter may undergo thermalreverse intersystem crossing to the singlet excited state prior toemission. Particularly preferred emitter-host systems include emittershaving phosphorescent or TADF emission, and a host with sufficientlyhigh excited triplet state (T1) to permit emission predominantly fromthe emitter, at the characteristic emission wavelength of the emitter.

In an embodiment, the first ethylenically unsaturated monomers containelectroactive groups including carbazoles and other heterocyclic groups,while the second ethylenically unsaturated monomers contain emittercompounds that include fluorescent emitters (defined as fluorescentsystem above), phosphorescent emitter containing iridium and thermallyactivated delayed fluorescence (TADF) emitters.

Examples of emitters are a substituted or unsubstituted sulfonylcompound, a substituted or unsubstituted carbazole compound, asubstituted or unsubstituted triazole compound, a substituted orunsubstituted acridine compound, a substituted or unsubstituted triazinecompound, a substituted or unsubstituted nitrile compound, a substitutedor unsubstituted phenylpyridine compound, a substituted or unsubstitutedphenoxazine compound, a substituted or unsubstituted fluorene compound,a substituted or unsubstituted oxadiazole compound, a substituted orunsubstituted xanthene compound, a substituted or unsubstitutedphenylamino compound, a substituted or unsubstituted phenazine compound,a substituted or unsubstituted arylboron-containing compound, anorganocopper compound, an organoplatinum compound, an organoiridiumcompound, an organopalladium compound, or a combination thereof.

The host moiety is a substituted or unsubstituted carbazole compound, asubstituted or unsubstituted triazole compound, a substituted orunsubstituted acridine compound, a substituted or unsubstituted triazinecompound, substituted or unsubstituted pyridine compound, a substitutedor unsubstituted phenoxazine compound, a substituted or unsubstitutedfluorene compound, substituted or unsubstituted phosphine-oxide,substituted or unsubstituted tetra-phenyl-silane, substituted orunsubstituted quinazoline, substituted or unsubstituted Be-complexes,substituted or unsubstituted oxadiazole, substituted or unsubstitutedbiphenyls, substituted or unsubstituted dibenzo furan, substituted orunsubstituted 1,3,5,2,4,6-triazatriphosphinine, substituted orunsubstituted dibenzocarbazole, substituted or unsubstituted anthracene,substituted or unsubstituted naphthalene, substituted or unsubstitutedphenanthrene, substituted or unsubstituted triphenylene, substituted orunsubstituted imidazole, substituted or unsubstituted benzimidazole,substituted or unsubstituted phenanthroline, substituted orunsubstituted spirofluorenes, substituted or unsubstituted silane or acombination thereof.

The HTL moiety is a substituted or unsubstituted tri-arylamine,substituted or unsubstituted carbazole compound, a substituted orunsubstituted acridine compound, a substituted or unsubstitutedphenoxazine compound, a substituted or unsubstituted fluorene compound,substituted or unsubstituted tetra-phenyl-silane, substituted orunsubstituted biphenyls, substituted or unsubstituted dibenzo furan,substituted or unsubstituted dibenzocarbazole, substituted orunsubstituted anthracene, substituted or unsubstituted naphthalene,substituted or unsubstituted phenanthrene, substituted or unsubstitutedtriphenylene, substituted or unsubstituted spirofluorenes, substitutedor unsubstituted silane or a combination thereof.

The ETL moiety is a substituted or unsubstituted carbazole compound, asubstituted or unsubstituted triazole compound, a substituted orunsubstituted triazine compound, substituted or unsubstituted pyridinecompound, a substituted or unsubstituted fluorene compound, substitutedor unsubstituted phosphine-oxide, substituted or unsubstitutedtetra-phenyl-silane, substituted or unsubstituted quinazoline,substituted or unsubstituted Al-complexes, substituted or unsubstitutedLi-complexes, substituted or unsubstituted oxadiazole, substituted orunsubstituted biphenyls, substituted or unsubstituted1,3,5,2,4,6-triazatriphosphinine, substituted or unsubstituteddibenzocarbazole, substituted or unsubstituted anthracene, substitutedor unsubstituted naphthalene, substituted or unsubstituted imidazole,substituted or unsubstituted benzimidazole, substituted or unsubstitutedphenanthrene, substituted or unsubstituted triphenylene, substituted orunsubstituted phenanthroline, substituted or unsubstitutedspirofluorenes, substituted or unsubstituted silane or a combinationthereof.

The HIL moiety is a substituted or unsubstituted tri-arylamine,substituted or unsubstituted carbazole compound, a substituted orunsubstituted acridine compound, a substituted or unsubstitutedphenoxazine compound, a substituted or unsubstituted fluorene compound,substituted or unsubstituted tetra-phenyl-silane, substituted orunsubstituted biphenyls, substituted or unsubstituted dibenzo furan,substituted or unsubstituted dibenzocarbazole, substituted orunsubstituted anthracene, substituted or unsubstituted naphthalene,substituted or unsubstituted phenanthrene, substituted or unsubstitutedtriphenylene, substituted or unsubstituted spirofluorenes, substitutedor unsubstituted silane, substituted or unsubstituted quinoxaline,substituted or unsubstituted aryl-florides, substituted or unsubstitutedthiophenes, substituted or unsubstituted aryl-sulphonates or acombination thereof.

Particularly preferred are carbazole, phenoxazine, hydroacridine andfluorene derivatives that also contain N-heterocycles includingtriazine, quinazolines, pyridines and pyrimidine. These compounds have asufficiently large band gap, as well as sufficiently high Ti and Sienergy states to allow emission from the emitter that emit well into theblue spectrum. They also tend to be less inclined to crystallize,offering the additional benefit of a more robust morphology.

A suitable carbazole derivative that can be used (as the first, thirdand fifth electroactive moieties) for forming the first block of thebrush polymer is given by the formula (1)

where at least one or more of X₁, X₂, X₃, X₄, X₅, X₆, X₇ and X₈ canindependently be a nitrogen atom or a C(R) functionality, where R isselected from a hydrogen atom, an ethylenically unsaturated moiety, asubstituted or unsubstituted C₁-C₆₀ alkyl group, a substituted orunsubstituted C₂-C₆₀ alkenyl group, a substituted or unsubstitutedC₂-C₆₀ alkynyl group, a substituted or unsubstituted C₁-C₆₀ alkoxygroup, a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, asubstituted or unsubstituted C₂-C₁₀ heterocycloalkyl group, asubstituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted orunsubstituted C₃-C₁₀ heterocycloalkenyl group, a substituted orunsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted C₆-C₆₀aryloxy group, a substituted or unsubstituted C₆-C₆₀ arylthio group, ora substituted or unsubstituted C₆-C₆₀ heteroaryl group. In anembodiment, X₁ and X₆ and/or X₄ and X₈ may be a bonded to form a fusedaromatic ring with A₁ and A₂.

In the formula (1), R^(a) and R^(b) are the same or different and areindependently a substituted or unsubstituted C₁-C₆₀ alkyl group, asubstituted or unsubstituted C₂-C₆₀ alkenyl group, a substituted orunsubstituted C₂-C₆₀ alkynyl group, a substituted or unsubstitutedC₁-C₆₀ alkoxy group, a substituted or unsubstituted C₃-C₁₀ cycloalkylgroup, a substituted or unsubstituted C₂-C₁₀ heterocycloalkyl group, asubstituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted orunsubstituted C₃-C₁₀ heterocycloalkenyl group, a substituted orunsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted C₆-C₆₀aryloxy group, a substituted or unsubstituted C₆-C₆₀ arylthio group, ora substituted or unsubstituted C₆-C₆₀ heteroaryl group. In the formula(1), m and n are independently 1 to 4 and can also assume values of 2 or3. R⁹ comprises an ethylenically unsaturated moiety. In an embodiment,the ethylenically unsaturated moiety is bonded to the aryl group or theheteroaryl group via a C₁-C₃₀ alkyl or via a C₃-C₃₀ cycloalkyl. Theethylenically unsaturated moiety is either a vinyl, norbornyl, anacrylate, a methacrylate, a styrene, an acrylamide, or a methacrylamide.

In one embodiment, in the formula (1), X1 and/or X4 are nitrogen atoms,while the remaining moieties X₂, X₃, X₅, X₆, X₇ and X₈ are C(R)functionalities, where R is a hydrogen atom. R^(a) and R^(b) arehydrogen atoms, with n and m both being equal to 1. R⁹ comprises anethylenically unsaturated moiety. In an embodiment, the ethylenicallyunsaturated moiety is bonded to the aryl group or the heteroaryl groupvia a C₁-C₃₀ alkyl or via a C₃-C₃₀ cycloalkyl. The ethylenicallyunsaturated moiety is either a vinyl, an acrylate, a methacrylate, astyrene, an acrylamide, or a methacrylamide.

In another embodiment, in the formula (1), X₁, X₂, X₃, and X₄ are allC(R) functionalities, where R is a hydrogen atom. At least one andpreferably two of X₅, X₆, X₇ and X₈ are nitrogen atoms, with theremainder being C(R) functionalities, where R is a hydrogen atom. R^(a)and R^(b) are hydrogen atoms, with n and m both being equal to 1. R⁹comprises an ethylenically unsaturated moiety. In an embodiment, theethylenically unsaturated moiety is bonded to the aryl group or theheteroaryl group via a C₁-C₃₀ alkyl or via a C₃-C₃₀ cycloalkyl. Theethylenically unsaturated moiety is either a vinyl, an acrylate, amethacrylate, a styrene, an acrylamide, or a methacrylamide.

In a preferred embodiment, in the formula (1), X₆ and X₈ are nitrogenatoms, while the remainder of X₁, X₂, X₃, X₄, X₅ and X₇ are all C(R)functionalities, where R is a hydrogen atom. R^(a) and R^(b) arehydrogen atoms, with n and m both being equal to 1. R⁹ comprises anethylenically unsaturated moiety. In an embodiment, the ethylenicallyunsaturated moiety is bonded to the aryl group or the heteroaryl groupvia a C₁-C₃₀ alkyl or via a C₃-C₃₀ cycloalkyl. The ethylenicallyunsaturated moiety is either a vinyl, an acrylate, a methacrylate, astyrene, an acrylamide, or a methacrylamide.

In yet another embodiment, in the formula (1), all of X₂, X₃, X₅, and X₇are C(R) functionalities, where R is a hydrogen atom, while at least oneof X₁ and X₆ or X₄ and X₈ are bonded together to form a substituted 5 or6 membered ring. R^(a) and R^(b) are hydrogen atoms, with n and m bothbeing equal to 1. R⁹ comprises an ethylenically unsaturated moiety. Inan embodiment, the ethylenically unsaturated moiety is bonded to thearyl group or the heteroaryl group via a C₁-C₃₀ alkyl or via a C₃-C₃₀cycloalkyl. The ethylenically unsaturated moiety may be a vinyl, anacrylate, a methacrylate, a styrene, an acrylamide, or a methacrylamide.

In an embodiment, R9 may be one of the structures depicted in formulas(2), (3) and (4).

where n in the formulas (2) and (3) is 1 to 40, preferably 2 to 20.

In an embodiment, with reference to the formula (1), at least one of thearomatic rings A₁ and A₂ can be a substituted or unsubstituted phenyl, asubstituted or unsubstituted pyridine, a substituted or unsubstitutedpyridazine, a substituted or unsubstituted pyrimidine, a substituted orunsubstituted pyrazine, a substituted or unsubstituted 1,2,4-triazine, asubstituted or unsubstituted 1,3,5-triazine, a substituted orunsubstituted 2H-thiopyran, a substituted or unsubstituted 2H-pyran, asubstituted or unsubstituted 4H-pyran, a substituted or unsubstituted1,4 dioxine, a substituted or unsubstituted 2H-thiopyran, a substitutedor unsubstituted 4H-thiopyran, a substituted or unsubstituted2H-1,2-oxazine, a substituted or unsubstituted 4H-1,2-oxazine, asubstituted or unsubstituted 6H-1,2-oxazine, a substituted orunsubstituted 2H-1,3-oxazine, a substituted or unsubstituted4H-1,3-oxazine, a substituted or unsubstituted 6H-1,3-oxazine, asubstituted or unsubstituted 4H-1,4-oxazine, a substituted orunsubstituted 2H-1,2-thiazine, a substituted or unsubstituted4H-1,4-thiazine, a substituted or unsubstituted 6H-1,2-thiazine, asubstituted or unsubstituted 2H-1,4-thiazine, or the like. In anexemplary embodiment, the aromatic ring A₂ is benzene, while the ring A₁is an unsubstituted pyrimidine.

Examples of carbazole derivatives that may be used as the firstethylenically unsaturated monomer include the structures of formulas(5)-(9):

where R⁹ comprises an ethylenically unsaturated moiety. In anembodiment, the ethylenically unsaturated moiety is bonded to the arylgroup or the heteroaryl group via a C₁-C₃₀ alkyl or via a C₃-C₃₀cycloalkyl. The ethylenically unsaturated moiety is either a vinyl, anacrylate, a methacrylate, a styrene, an acrylamide, or a methacrylamide.

A preferred carbazole derivative is that can be used for forming thefirst block of the brush polymer is2-(2-(4-(9H-carbazol-9-yl)phenyl)pyrimidin-5-yl)ethyl methacrylate(M6MA) shown by the formula (10) below

The second ethylenically unsaturated monomer may also serve as aphotocatalyst for the polymerization reaction of the first ethylenicallyunsaturated monomer. Alternatively, a non-polymerizable photocatalystmay be used. The repeat units of the second ethylenically unsaturatedmonomer comprises a metal-complex shown in the formula (11). These metalcomplexes which are used in the second electroactive moiety, the fourthelectroactive moiety and the sixth electroactive moiety are preferablyemitter moieties and are described below in the formula (11).

wherein, in the formula (11), M is iridium (Ir), osmium (Os), platinum(Pt), gold (Au), ruthenium (Ru), copper (Cu); and at least one of R^(c)or R^(d) is an ethylenically unsaturated moiety. The ethylenicallyunsaturated moiety may be covalently or ionically bonded to thecarbazole moiety through a C₁-C₃₀ alkyl or via a C₃-C₃₀ cycloalkyl. Theethylenically unsaturated moiety may be a vinyl, an acrylate, amethacrylate, a styrene, an acrylamide, or a methacrylamide.

In an embodiment, one of R^(c) or R^(d) comprises an ethylenicallyunsaturated functionality, while the other functionality isindependently selected from a hydrogen, a halogen atom, a substituted orunsubstituted C₁-C₁₀ alkyl group, a substituted or unsubstituted C₂-C₁₀alkenyl group, a substituted or unsubstituted C₁-C₁₀ alkoxy group, asubstituted or unsubstituted C₃-C₁₀ cycloalkyl group, a substituted orunsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted orunsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or unsubstitutedC₁-C₁₀ heterocycloalkenyl group, a substituted or unsubstituted C₆-C₂₄aryl group, a substituted or unsubstituted C₆-C₂₄ aryloxy group, asubstituted or unsubstituted C₆-C₂₄ arylthio group, and a substituted orunsubstituted C₆-C₃₀ heteroaryl group.

In the formula (11), L′ and L″ are the same or different, and are each abidentate ligand. In the formula (11), q and r are each independently aninteger of 1 to 4.

In an embodiment, the second ethylenically unsaturated monomer isbis[[2-(X)]4-(pyridin-2-yl)oxymethylmethacrylate]-iridium(III) (referredto as iridium-X-methacrylate (IrXMA), where the X represents the C^N inthe formula (12) below. The second ethylenically unsaturated monomer hasthe structure shown in the formulas (12) and (13) or (12) and (14):

wherein in the formula (12), R^(e) is a hydrogen atom, a cyano group, ahalogen atom, a substituted or unsubstituted C₁-C₃₀ alkyl group, asubstituted or unsubstituted C₂-C₁₀ alkenyl group, a substituted orunsubstituted C₁-C₁₀ alkoxy group, a substituted or unsubstituted C₃-C₁₀cycloalkyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkylgroup, a substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, asubstituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, asubstituted or unsubstituted C₆-C₂₄ aryl group, a substituted orunsubstituted C₆-C₂₄ aryloxy group, a substituted or unsubstitutedC₆-C₂₄ arylthio group, and a substituted or unsubstituted C₆-C₃₀heteroaryl group, and where C^N may be represented by the structureshown in the formula (13)

where R¹⁰ to R²¹ are each independently a hydrogen atom, a cyano group,a halogen atom, a substituted or unsubstituted C₁-C₃₀ alkyl group, asubstituted or unsubstituted C₂-C₁₀ alkenyl group, a substituted orunsubstituted C₁-C₁₀ alkoxy group, a substituted or unsubstituted C₃-C₁₀cycloalkyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkylgroup, a substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, asubstituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, asubstituted or unsubstituted C₆-C₂₄ aryl group, a substituted orunsubstituted C₆-C₂₄ aryloxy group, a substituted or unsubstitutedC₆-C₂₄ arylthio group, and a substituted or unsubstituted C₆-C₃₀heteroaryl group; and where X¹⁰ is oxygen or sulfur. In an embodiment,any of the adjacent groups of R¹⁰ through R²¹ may be fused together toform an aryl ring. “n” in the formula (12) can be 1 or 2. In anexemplary embodiment, M is Ir.

Examples of C^N (also referred to as M₁) (C^N refers to a ligand thatcoordinates through one carbon atom and one nitrogen atom to a metalcenter) are shown in the plurality of structures shown in the formulas(15a) through (15f), where structure (15a) below isdifluorophenylpyridine (dfppy):

where structure (15b) below is phenylpyridine (ppy)

where structure (15d) is phenyl-isoquinoline (piq)

where structure (15e) below is also phenylquinoline (pq)

where structure (15f) below is benzothiophenylpyridine (btp)

Other emitters and/or electroactive materials that can be covalentlybonded to the ethylenically unsaturated monomers include the structuresshown below in formula (15g). The covalent bonding occurs throughoptional substitution of an ethylenically unsaturated group anywherethere is a C—H bond.

Other electroactive moieties emitters that may be covalently bonded tothe ethylenically unsaturated moieties include the structures shown inthe formula (15h) below. The covalent bonding occurs through optionalsubstitution of an ethylenically unsaturated group anywhere there is aC—H bond.

Examples of electroactive materials, which can be attached to polymerbackbone are shown in the formula (15i)

Examples of fluorescent and phosphorescent emitter molecules, which canbe pendent to the polymer backbone are shown in the formula (15j) below

Examples of TADF emitter molecules, which can be attached to a polymerbackbone are shown below in the formula (15k)

In an embodiment, the second ethylenically unsaturated monomer has astructure of the formula (16):

An exemplary brush polymer is shown in the formula (17) below

where “l” and “j” are repeat units in the formula (17) and M₁ is ahalogen, examples of which are bromine, chlorine or iodine. In anembodiment, “l” is 1 to 10000 and “j” is 1 to 10000, while M₁ is bromineor hydrogen. As noted above, the bromine may be removed during thepolymerization reaction or after the polymerization reaction. The M₁group is removed if desired.

In an embodiment, the ratio of l to j in the first region, in the secondregion and the third region is 1000:1 to 5:1. In one embodiment, theamount of the emitter moiety in the brush polymer (the first, secondand/or third brush polymer) is 0.1 to 15 mole percent.

In yet another embodiment, the brush polymer may be a diblock copolymerwith a first block that comprises a homopolymer and the second blockcomprises a random copolymer comprising units of the first ethylenicallyunsaturated monomer and the second ethylenically unsaturated monomer.The homopolymer may comprise units of the first ethylenicallyunsaturated monomer and the second ethylenically unsaturated monomer.Ethylenically unsaturated monomers of the formulas (1) and (5) through(10) above may be used in the homopolymer (that forms the first block)and in the random copolymer that is part of the second block.Ethylenically unsaturated monomers of the formulas (11) through (16) maybe used in the homopolymer as well as in the random copolymer that ispart of the second block.

In an exemplary embodiment, the brush polymer has the structure offormula (18)

where l, k and j in formula (18) represent the number of repeat unitsrespectively and M₁ represents a halogen, examples of which arechlorine, bromine or iodine. In an embodiment, l ranges from 1 to 10000,k ranges from 1 to 10000, and j ranges from 1 to 10000, and M₁ isbromine or hydrogen.

In one embodiment, in one manner of manufacturing the OLED display, thefirst ethylenically unsaturated monomer and the second ethylenicallyunsaturated monomer in the desired ratio (e.g., the first ratio) aremixed with a suitable solvent and are then disposed on a first region ofthe substrate. Other regions of the substrate are covered with a mask.The polymerization is then conducted using electromagnetic radiation toform the first brush polymer. Preferred radiation is UV or visiblelight. When the polymerization in the first region is completed, thesubstrate is (optionally) washed with a solvent, and the firstethylenically unsaturated monomer and the second ethylenicallyunsaturated monomer in the desired ratio (e.g., the second ratio) aremixed with a suitable solvent and are then disposed on a second regionof the substrate. Other regions of the substrate are covered with amask. The polymerization is again conducted using electromagneticradiation to form the second brush polymer in only the second region.Other regions of the substrate may have brush polymers disposed thereonin a similar manner. The substrate may be washed between eachpolymerization step.

In another embodiment, the first ethylenically unsaturated monomer andthe second ethylenically unsaturated monomer in the desired ratio (e.g.,the first ratio) are mixed with a suitable solvent and are then disposedon the entire substrate. Portions of the region are irradiated withelectromagnetic radiation while other regions are covered with aphotomask. When the exposed regions are reacted, the mask is thenremoved, subjecting the other regions to the radiation to effect thereaction.

The solvent is preferably one that can dissolve the reactants involvedin the manufacture of the polymer brush. In an embodiment, it ispreferable for the solvent to dissolve the first ethylenicallyunsaturated monomer, the second ethylenically unsaturated monomer orboth the first ethylenically unsaturated monomer and the secondethylenically unsaturated monomer. Depending upon the chemistry of thefirst ethylenically unsaturated monomer and the second ethylenicallyunsaturated monomer the solvent may be a protic or an aprotic polarsolvent. Aprotic polar solvents such as propylene carbonate, ethylenecarbonate, ethyl acetate, chloroform, butyrolactone, acetonitrile,benzonitrile, nitromethane, nitrobenzene, sulfolane, dimethylformamide,N-methylpyrrolidone, dimethylacetamide, anisole, o-xylene, p-xylene,m-xylene, or the like, or a combination thereof are generally desirable.Polar protic solvents such as, but not limited to, water, methanol,ethanol, propanol, isopropanol, butanol, or the like, or a combinationthereof may be used. In some embodiments, solvents which have fewerenvironmental negative impacts, or toxicological negative impact may bepreferentially selected. Solvents are used in an amount of at least 0.5wt %, based on a total weight of a reaction mixture.

In an embodiment, UV radiation have a wavelength of 350 to 600,preferably 400 to 500 nanometers is used to effect the functionalizationof the substrate and/or the polymerization of the first ethylenicallyunsaturated monomer and the second ethylenically unsaturated monomer. Inan embodiment, the intensity of the UV radiation can be 0.001 to 5000mW/cm², preferably 0.01 to 100 mW/cm² and more preferably 0.1 to 5mW/cm². In an embodiment, the substrate is irradiated for 3 to 400minutes, preferably 4 to 100 minutes and more preferably 5 to 10minutes.

In another embodiment, the substrate with the ethylenically unsaturatedmonomers disposed thereon may be irradiated with visible light at anintensity of 0.001 to 5000 milliwatts per square centimeter (mW/cm²). Inan embodiment, the intensity of the visible light can be 0.001 to 100mW/cm², preferably 0.01 to 10 mW/cm², and more preferably 0.1 to 1mW/cm². In an embodiment, the substrate with the with the ethylenicallyunsaturated monomer disposed thereon is irradiated for 3 to 400 minutes,preferably 4 to 100 minutes and more preferably 5 to 10 minutes. In anembodiment, a photomask having filters that permits the use of two ormore different light intensities (at the same time) may be employed.This provides a method to grow different thicknesses (potentially withina single pixel).

In one embodiment, by varying the molar ratio of the first ethylenicallyunsaturated monomer to the second ethylenically unsaturated monomer(i.e., by varying the ratio of the electroactive moiety to the emitter),or by varying the chemistry (the chemical structure) of theelectroactive moiety and the emitter, light of different wavelengths maybe emitted by the organic light emitting device.

In an exemplary embodiment, when the first ethylenically unsaturatedmonomer has the structure of formula (10) above and the secondethylenically unsaturated monomer has the structure of formula (16),varying the ratio of the second ethylenically unsaturated monomer to thefirst ethylenically unsaturated monomer can produce light of differentwavelengths. The molar ratio of the electroactive moiety to the emittercan be varied from 1000 to 1.

In an embodiment (when the first ethylenically unsaturated monomer hasthe structure of formula (10) above and the second ethylenicallyunsaturated monomer has the structure of formula (16)), for blue light,the molar ratio of the first ethylenically unsaturated monomer to thesecond ethylenically unsaturated monomer can be very large (e.g.,1:100,000 to 1:infinity). In this embodiment, there is no secondethylenically unsaturated monomer used in the manufacturing of the brushpolymer. Put another way, the first region of the substrate comprises abrush polymer that comprises only a single block produced by thepolymerization of the structure of formula (10). The resulting brushpolymer is a homopolymer. The light emitted by this brush polymer has afirst wavelength. The first wavelength is 380 to 500 nanometers.

In this embodiment (when the first ethylenically unsaturated monomer hasthe structure of formula (10) above and the second ethylenicallyunsaturated monomer has the structure of formula (16)), in order to emitlight having a wavelength of 380 to 500 nanometers (e.g., blue light),the molar ratio of the electroactive moiety to the emitter can be variedfrom 1000:1 to 1:3. In order to emit light having a wavelength of 460 to680 nanometers (green light), the molar ratio of the electroactivemoiety to the emitter can be varied from 1000:1 to 1:3. In order to emitlight having a wavelength of 560 to 740 nanometers (red light), themolar ratio of the electroactive moiety to the emitter can be variedfrom 1000:1 to 1:3.

In yet another embodiment, by varying the chemistry of the firstethylenically unsaturated monomer and the second ethylenicallyunsaturated monomer that are used to form the brush polymer, thewavelength of light emitted by different regions of the substrate can bevaried. In this embodiment, the first ethylenically unsaturated monomermay have the structure of any one of formulas (1) and (5) through (10)while the second ethylenically unsaturated monomer may have thestructure of any one of formulas (11) through (16). In an exemplaryembodiment, the first ethylenically unsaturated monomer has thestructure of formula (10) while the second ethylenically unsaturatedmonomer has the structure of any one of the moieties shown in theformula (12) through (15f). The wavelength of emitted light may varyfrom 380 to 740 nanometers depending upon the structures selected forthe first ethylenically unsaturated monomer and the second ethylenicallyunsaturated monomer.

According to an embodiment, a device including the block copolymer brushcan be formed by a method described herein. According to an embodiment,the device is a light emitting diode. In an embodiment, the device is anorganic electronic device including at least two electrodes and asemiconducting layer comprising at least one hole-transportingsemiconducting material or at least one electron-transportingsemiconducting material, wherein the at least one of the semiconductingmaterials is a semiconducting polymer brush that is covalently orionically bonded to the surface of at least one of the electrodes.

An advantage of the novel iridium (III) photocatalysts is that they canbe used to grow patterned, electronically active, polymer brushes fromindium tin oxide (ITO) using visible light. Notably, the iridium (III)species can act in three roles 1) as photocatalysts to initiate/mediatepolymerization, 2) as comonomers with a carbazole-based electroactivemoiety and 3) as phosphorescent emitters. The brush polymers developedherein may be used to produce OLEDs that emit different colors dependingupon the ratios of the host to the emitter. Different colors may also beproduced by combining different ethylenically unsaturated monomers inthe blocks.

Low energy visible light is used to graft patterned emissive polymerbrushes from ATRP initiator functionalized ITO. Novel iridium complexesbearing a pendent methacrylate (IrXMA) are synthesized and utilized forthe dual purpose of catalyzing/mediating controlled radicalpolymerization and harnessing triplet energy through radiativephosphorescence. The grafting of semiconducting methacrylate-basedbrushes using photo-ATRP provided emission spanning the visiblespectrum, from blue to red, dictated by the ligand (X) of the iridiumcomplex or lack thereof. Moreover, the iridium (Ir) emitter contentwithin the brushes is controlled by the monomer feed ratio. Theproduction of high resolution micron sized features and control overbrush thickness with irradiation time demonstrate spatiotemporal controlwith this procedure. Moreover, the generation of electronically activediblock copolymer architectures is possible. The facile fabrication ofred, green, and blue pixel arrays for white emission and a workingmulticolored OLED prototype showcased the utility of this methodologyfor display applications.

As noted above, the article disclosed herein may be used as an emissivelayer in a display. FIG. 9 depicts one exemplary embodiment of a display100. In an embodiment, a display device comprises a substrate 102 uponwhich is disposed in sequence an anode 104, a hole transport layer 106,an emission layer 108, an electron transport layer 110 and a cathode112. The emission layer 108 comprises the brush polymers and copolymersdisclosed herein. The emission layer comprising the brush polymers maythus have layers of other materials or emitters disposed below themand/or above them. In an embodiment, the substrate 102 is an opticallytransparent substrate. The anode 104 may be an indium tin oxide anode.Materials for the hole transport layer 106 and the electron transportlayer 110 are previously described in formulas (1) through (15g). Theemissive electroluminescent layer is a film of organic compound thatemits light in response to an electric current.

In another embodiment with reference to the FIG. 9, the brush polymermay comprise electroactive moieties that are used to form each of thelayers 106, 108 and 110 shown in the FIG. 9. For example, a firstelectroactive moiety reactively bonded to the polymer backbone maycomprise a hole transport layer moiety, the second electroactive moiety(also reactively bonded to the polymer backbone) may comprise the hostmoiety, the third electroactive moiety (also reactively bonded to thepolymer backbone) may comprise the emitter moiety, a fourthelectroactive moiety (also reactively bonded to the polymer backbone)may comprise the electron moiety, and so on. Temporal control may beused to achieve this particular layering of the different electroactivemoieties of the brush polymer. After the polymerization, the cathode 112may be added to the plurality of layers described above to form adisplay.

In an embodiment, the display devices may be a pixelated light emittingdiode that can emit light of single color (a single wavelength) or of aplurality of colors (light having different wavelengths). For example,it can emit white light or can emit red, green and blue light that canbe combined to produce white light. The article may be used to producelight in the entire visible light spectrum.

In an embodiment, the display device may be a micro organic lightemitting diode or a white organic light emitting diode (WOLED). TheWOLED may have a color conversion layer. The color conversion layer maycomprise periodical nanospheres that help extract the confined light inthe device and also increase the effective light path to achieve moreefficient color conversion.

The emissive layer disclosed herein may be used in flat displays, curveddisplays, transparent displays and in multilayer displays.

The emissive layer disclosed herein may be used as lighting such as, forexample, white lighting, red lighting, conformal light coatings, coloradjusting lighting, lighting for sign boards, or the like.

In an embodiment, the plurality of brush polymers form an emissive layerthat emits fluorescent light and/or phosphorescent light. In anotherembodiment, the plurality of brush polymers further form at least one ofa host emission layer, a hole transport layer, a hole injection layerand/or an electron transport layer in addition to the emissive layer;and where at least one of the host emission layer, a hole transportlayer, a hole injection layer and/or an electron transport layer contactthe emissive layer.

In an embodiment, the emissive layer is part of an electroemissivedevice that contains a cathode and an anode disposed on opposing sidesof the emissive layer.

In another embodiment, a device comprising the emissive layer comprisesa display that comprises light emitting pixels that are activated todisplay individual colors or color combinations.

In another embodiment, the device is a light source that emits light ofa single color or of a plurality of colors. In an embodiment, the deviceemits white light. The emitted light is transmitted through a colorconversion layer. The color conversion layer comprises a multiplicity ofpixels of a multiplicity of colors.

In an embodiment, the device is a light emitting diode. In yet anotherembodiment, the device is a white organic light emitting diode.

The emissive layer disclosed herein may be used as lighting such as, forexample, white lighting, red lighting, conformal light coatings, coloradjusting lighting, lighting for sign boards, or the like.

It should be understood that the exemplary embodiments described thereinshould be considered in a descriptive sense only and not for purposes oflimitation. Descriptions of features or aspects within each exemplaryembodiment should typically be considered as available for other similarfeatures or aspects in other exemplary embodiments.

The invention is exemplified by the following non-limiting examples.

EXAMPLE

The following components are used in the examples. Unless specificallyindicated otherwise, the amount of each component is in weight percentin the following examples, based on the total weight of the composition.

Physical measurements were made using the tests and test methodsdescribed below. Light sources. 405 nm (model M405L3-C1) and 465 nm(model M470L3-C1) collimated light emitting diodes were run through aT-Cube LED driver (model LEDD1B) (power supply unit—KPS101), allpurchased from ThorLabs. The light intensity was measured using anattenuated photodiode detector purchased from Newport Corporation (Model818-UV/DB). Spectrophotometer with cosine corrector and radiometriccalibration was purchased from Ocean Optics (model USB 4000) and used tomeasure the LED emission profile.

Optical micrographs were captured with a Nikon Elipse E600 opticalmicroscope in reflectance mode and a Keyence VHX-5000 digitalmicroscope.

Tapping mode AFM experiments were performed using a MFP-3D system(Asylum Research, Santa Barbara, Calif.) to identify patterned polymerbrushes and determine brush thicknesses. The measurements were conductedusing commercial Si cantilevers.

XPS was performed using a Kratos Axis Ultra Spectrometer (KratosAnalytical, Manchester, UK) with a monochromatic aluminum Kα X-raysource (1486.6 eV) operating at 225 W under a vacuum of 10−8 Torr andspectra were analyzed using CasaXPS software.

SIMS imaging was performed using a Camera IMS 7f system (Camera SAS,Gennevilliers, France). A 10 kV Cs+ ion beam and 5 kV negative samplepotential were used, for a total impact energy of 15 kV.

Example 1

This example demonstrates the method of manufacturing an OLED on anindium tin oxide ITO substrate.

In this example, indium tin oxide (ITO) is chosen as the grafting-fromsubstrate due to its well established utility as a transparent electrodein organic electronics. Alkenes are grafted to ITO substrate using UVlight, which uniquely provides spatial control.

With reference again to the FIG. 1, the ITO functionalization is startedwith base piranha or air plasma treatment to expose surface hydroxyls,followed by deposition of 5-hexeneol onto the surface and irradiatingwith 254 nm UV light (2 mW/cm²) for 16 hours (Scheme 1, step 1).Subsequently, the functionalized ITO is acylated with α-bromoisobutyryl(BIBB), then briefly sonicated (˜1 min) to clean the surface ofphysisorbed material.

X-ray photoelectron spectroscopy (XPS) confirms the presence of aninitiator layer through detection of bromine (Br3p at 185 eV) andcarbonyl (C1s, C═O at 289 eV) functionalities. Light-mediated atomtransfer radical polymerization (photo-ATRP) is accomplished with twomonomer derivatives,2-(2-(4-(9H-carbazol-9-yl)phenyl)pyrimidin-5-yl)ethyl methacrylate(M6MA) (see Formula (10)), andbis[[2-(X)]4-(pyridin-2-yl)oxymethylmethacrylate]-iridium(III) (IrXMA)(see Formula (16)), where X represents the C^N ligands that dictatetriplet energy (T1), and thus emission color, as energy is transferredfrom M6MA (host) to IrXMA (emitter) (vide infra).

N-Methyl-2-pyrrolidone (NMP) is selected as the solvent because of itsability to effectively dissolve the monomers and corresponding linearpolymers prepared using free radical polymerization. A typicalgrafting-from procedure is as follows: In a glovebox a 1M solution ofM6MA (˜20 mg)+IrXMA (1-12 mol % for copolymers) in NMP was placed ontoinitiator functionalized ITO, followed by laying a glass coverslip orphotomask onto the solution, and illuminating with visible light (Scheme1, step 2). Although both 405 and 465 nm collimated LEDs were found tobe effective, the 465 nm light (0.4 mW/cm²) is used for mostcopolymerizations due to its deeper penetration through the solution,given ˜2-3× less absorption by IrXMA at 465 nm relative to 405 nm.

In other words, reduced light attenuation provides more active photonsat the ITO/monomer interface. After irradiation, the polymer-brushcoated substrates were washed thoroughly with CH₂Cl₂ using sonication orSoxhlet extraction.

Initially, M6MA homopolymer brushes were grafted from ITO, usingIr(ppy)3 (0.005 mol %) as the photocatalyst and 405 nm irradiation (4mW/cm2). The resulting brushes emitted a bright blue fluorescence(λmax=405 nm) under UV excitation (λex=365 nm), characteristic ofpoly(M6MA).

Example 2

This example was conducted to demonstrate how changing the chemistry ofthe second ethylenically unsaturated monomer will change the wavelengthof light emitted by the brush polymer.

Substituting Ir(ppy)3 with IrXMA (1-12 mol %), where X represents theC^N ligands difluorophenylpyridine (dfppy), phenylpyridine (ppy),phenylquinoline (pq), or benzothiophenylpyridine (btp), and growingbrushes using 465 nm irradiation (0.4 mW/cm²) provided a library ofpolymer brushes having green-blue, green, orange, and redphosphorescence, respectively. FIG. 2 shows the different C^N (X) groupsand the graph depicts the corresponding emitted light of differentwavelengths. Due to the larger quantities of photocatalyst/emitter usedvery little energy input is used for copolymer brush growth. The energyis as low as 0.04 mW/cm² (405 nm), which is one to two orders ofmagnitude less than that used for other controlled photopolymerizations.

Photoluminescence measurements (λ_(ex)=340 nm) of the copolymer brushesshowed emission profiles, with λ_(max) ranging from 490-600 nm, with noresidual fluorescence from the host (M6MA), which suggests excellentenergy transfer to the Ir(III) emitters. The efficient energy transferis due to the high triplet energy (T1) of the M6MA host (T1≈2.8 eV),relative to the IrXMA emitters (T1≤2.7 eV).

A survey of the surface with XPS confirmed the chemical compositions forthe five different brushes, showing distinct N1s peaks (400 eV) for allfive brushes, Ir4f peaks (60 eV) for the four copolymers, as well as F1speaks (687 eV) for poly(M6MA-co-IrdfppyMA) brushes and S2s (228 eV) andS2p (164 eV) peaks for poly(M6MA-co-IrbtpMA) brushes. Moreover, noresidual indium (444 eV) or tin (485 eV) signals are observable with XPSfor the five brush samples, suggesting uniform coverage with thicknessesexceeding ˜10 nm.

Example 3

This example is conducted to demonstrate how changing the molar ratio ofthe second ethylenically unsaturated monomer to the first ethylenicallyunsaturated monomer may be used to change the wavelength of lightemitted.

The host to emitter ratio affects the overall OLED device performance,and as such it is desirable to have control over the relativeincorporation of Ir. To test whether the feed ratio of IrXMA correlatedwith the incorporation, five different polymer brushes were grafteduniformly from ITO using variable amounts of IrppyMA (0, 1, 3, 6, and 12mol % respectively). XPS was used to determine the chemical compositionof the five different films showing a clear increase in the Ir4f_(7/2)and Ir4f_(5/2) signals at binding energies of 60 and 63 eV,respectively, as the IrppyMA loading was increased. FIG. 3A depicts theXPS that was used to determine the chemical composition of the fivedifferent films.

FIG. 3B is a graph that shows that the atomic percent of Ir, relative tocarbon, oxygen, and nitrogen, is in good agreement with theoreticalvalues. Notably, the atomic percent of Ir, relative to carbon, oxygen,and nitrogen, is in good agreement with theoretical values, albeittypically lower than targeted (0.4, 2.6, 4.4 and 9.7 mol % Ir detectedfor 0, 1, 3, 6, and 12 mol % loading). The lower than theoretical valuesmay be due to common organic contaminants containing carbon, oxygen, andnitrogen. Additionally, photoluminescence measurements on the fourcopolymer samples revealed a slight bathochromic shift and broadening ofemission for higher IrppyMA loadings, which can be observed in thephotoluminescence images (λ_(ex)=365 nm) provided as an inset in FIG.3A. The notable red-shift and broadening is consistent with theanalogous spun-cast linear polymer samples as Ir emitter content isincreased. Specifically, for the 1, 3, 6, and 12 mol % IrppyMA loadedbrushes on ITO a λ_(max) of 514, 518, 521, and 525 nm, respectively, ismeasured, while, congruently, a full width at half maximum (FWHM) of 76,79, 81, and 83 nm is calculated. The XPS and photoluminescencemeasurements indicate that this methodology can be used effectively totarget polymer brushes with specific emitter contents to achieve optimaldevice performance.

Example 4

This example is used to demonstrate the ability to regulate graftingposition (e.g., spatial control) that is used for multicolored pixelarrays and can be achieved with the use of photomasks. FIG. 4 (see Step1) shows the use of spatial control during initiator functionalizationor during photopolymerization (see Step 2). FIGS. 4A and 4B exemplifyspatial control demonstrated with poly(M6MA-co-IrppyMA) brushescontaining ˜6 mol % IrppyMA, and irradiation through a chrome coatedquartz photomask at either step 1 (UV) or step 2 (visible light). FIG.4A depicts a schematic representation of the functionalization, whileFIG. 4B depicts corresponding reflectance and photoluminescence images(step 1—left, and step 2—right).

First, spatial control during initiator functionalization (step 1)occurs by placing a chrome coated quartz photomask with millimeter sizedtransparent rectangles onto 5-hexeneol that is layered on top of apre-cleaned ITO substrate, followed by irradiating the sample for 4hours through the photomask using a 254 nm UV capillary light source (6mW/cm²). After acylation with BIBB the ATRP initiator functionalizedsubstrate is coated with a 1M solution of M6MA and IrppyMA (6 mol %) inNMP, sandwiched with a non-patterned glass coverslip on top, anduniformly irradiated for one hour.

Reflectance and photoluminescence imaging indicated preferential growthof polymer brushes in the regions that were exposed to UV light duringstep 1 (FIG. 4, left side). However, careful observation of the emissionimage revealed minor brush growth outside of the rectangles, which islikely due less efficient acylation of ITO surface hydroxyls with BIBB.Alternatively, uniform initiator functionalization, followed byirradiation with visible light (465 nm) through the same photomask (mask1) provides the same polymer brushes, poly(M6MA-co-IrppyMA), withlittle-to-no observable photoluminescence outside the regions that wereirradiated (FIG. 4, right side, see step 2).

Example 5

This example is used to demonstrate a correlation between reflectancecolor and thickness of patterned polymer brushes that were grown fordifferent lengths of time. To establish a correlation betweenreflectance color and thickness, patterned polymer brushes were grownfor different lengths of time, which simultaneously provided insightinto temporal control. Initially a chrome coated glass photomask withhorizontal 20×200 μm transparent rectangles was used to grow poly(M6MA)brushes using 405 nm light (4 mW/cm²) with four different irradiationtimes (10, 40, 60, and 120 min.). Subsequently, a similar photomask, butwith vertical 200×20 μm transparent rectangles was used to grow the samehomopolymer under identical grafting conditions, with four differentirradiation times (20, 45, 60, and 90 min.).

FIGS. 5A-5D depict one manner of achieving temporal control usingpatterned poly(M6MA) and poly(M6MA-co-IrppyMA) brushes on ITO. FIG. 5Ashows reflectance (left) and photoluminescence (right) images of 220×200 μm lines grown for different lengths of time (40 and 60 min. forhorizontal and vertical, respectively) and interwoven to providedifferent heights (43, 55, and 85 nm for horizontal, vertical, andintersection, respectively). FIG. 5B depicts a 3D topographical image ofa pattern obtained using AFM. FIG. 5C shows correlation betweenreflectance color and brush thickness; boxed regions are images ofsections measured with AFM and regions between are generated colorgradients. FIG. 5D shows reflectance (top) and photoluminescence(bottom) images of copolymer brush squares at different time intervals,with 6 mol % IrppyMA used as catalyst/emitter.

The resulting interwoven patterns contain three different brushthicknesses within a small 40 μm² window, corresponding to 1) horizontallines, 2) vertical lines and 3) their 20×20 μm square point ofintersection as shown in FIG. 5A. On two substrates four differentregions each containing three brush heights were generated, providing atotal of 24 different color/thickness data points for all images). Thedifferent brush thicknesses were evident in the reflectance images (FIG.5A) and confirmed using atomic force microscopy (AFM) (FIG. 5B).

For best precision, a common cold white LED source was used for allreflectance imaging and the color coordinates (L*, a*, b*) weredetermined as a means of quantification. AFM revealed thicknesses up to120 nm, which were correlated to the respective reflectance colors togenerate a gradient as shown in FIG. 5C. In the FIG. 5C, the boxedregions are actual reflectance images, with their center denoted by across that corresponds to the specific thickness on the axis, while the2-point color gradients in between each boxed region was generated fromthe respective L*,a*,b* values as a representation of the theoreticalcolor for a given thickness.

The distinct color variations for minute changes in brush thicknessallows for a relatively accurate (±10 nm) and rapid determination ofbrush height by simply observing the color of reflected light. Inaddition, from these results emerged a clear correlation betweenpolymerization time and brush thickness, which is evidence for temporalcontrol.

Specifically, 6 mol % IrppyMA is copolymerized with M6MA using 465 nmirradiation (0.4 mW/cm²) through chrome-coated glass photomasks withmillimeter sized transparent square masks.

Both reflectance and photoluminescence images shown in FIG. 5D suggestthat brush thickness increases with time, where reflectance color can beroughly correlated with thickness using FIG. 5C, providing ˜15, 40, 60and 80 nm for 5, 10, 20 and 40 minutes of irradiation, respectively.

Moreover, the increase in observable emission intensity over timecorrelates with an increase in brush thickness (λ_(ex)=365 nm). Thus,temporal control for copolymer brushes using high catalyst loadings isreadily accessible with this approach.

Example 6

This example demonstrates the manufacturing of diblock brush polymerswhere the first block is a homopolymer manufactured from a firstethylenically unsaturated monomer, while the second block is a randomcopolymer that comprises repeat units of a first ethylenicallyunsaturated monomer and a second ethylenically unsaturated monomer.

This example also demonstrates that the bromide chain-ends were stillexistent/active after brush formation thus permitting the formation ofthe fabricating diblock copolymer architectures. From an OLED deviceperspective this provides an effective way to grow complex arrays wherethe first block may be a hole transporting layer (HTL) and the secondblock an emissive layer (EML), both with pre-defined thicknessescontrolled through irradiation time. The hole transporting layercomprises poly(M6MA) as the first block, reacted over a large area ofapproximately 7×12 mm on a 15×20 mm initiator functionalized ITOsubstrate. After thorough washing, the copolymer brushes containing M6MAand IrppyMA (3 mol %) were grown through a mask 3 containing vertical200×20 μm rectangles and spans approximately a 13×18 mm square area ofthe substrate.

This provides four distinct regions on one substrate; 1) ATRP initiatorfunctionalized ITO, 2) poly(M6MA) homopolymer, 3) poly(M6MA-co-IrppyMA)random copolymer, and 4) poly(M6MA-b-(M6MA-co-IrppyMA) block copolymer.FIG. 6A depicts a representation of polymer brushes on ITO and chemicalstructure for poly(M6MA-b-(M6MA-co-IrppyMA)). FIG. 6B depicts areflectance image showing four distinct regions: 1. ATRP initiatorfunctionalized ITO; 2. poly(M6MA); 3. poly(M6MA-co-IrppyMA); and 4.poly(M6MA-b-(M6MA-co-IrppyMA)). FIG. 6C depicts a photoluminescenceimage of the image of FIG. 6B, while FIG. 6D shows a SIMS showingoverlay of ¹²C ¹⁴N (color) and ¹¹⁵In ¹⁶O (greyscale).

FIG. 6A shows different reflectance colors for each region, with acorresponding brush thickness of ˜50, 60 and 90 nm for regions 2, 3, and4, respectively, while the photoluminescence image indicates that theemitter resides only in the 20×200 μm rectangles (greenphosphorescence). The surface was further characterized with secondaryion mass spectrometry (SIMS), showing only an indium signal (from theindium tin oxide substrate) in the unexposed regions, while nitrogen isfound everywhere else, which attests to the excellent spatial controlobtainable with this methodology. The reflectance, photoluminescence,and SIMS characterization suggests that the bromide chain end is activeafter initial brush formation, allowing for re-initiation and growth ofa second luminescent block.

Example 7

This example demonstrates that the high degree of spatial controlachievable with the brush polymers allows for the preparation ofmulticolored pixel arrays that are often utilized to generate whitelight for display applications. FIGS. 7A-7D are used to show whiteemission from a red, green, and blue pixel array. FIG. 7A showsphotoluminescence images (λ_(ex)=365 nm) of the three step RGBG arrayfabrication, going from red (poly(M6MA-co-IrbtpMA); 500×500 μm), togreen (poly(M6MA-co-IrppyMA); 125×750 μm), to blue (poly(M6MA); 500×750μm) pixels. FIG. 7B shows a photoluminescence microscopy image(λ_(ex)=365 nm) showing a magnification of the final pixelated sample(as indicated by the dotted white box in “FIG. 7A”). FIG. 7C shows aphotoluminescence profile of the pixel array overlaid with individualred, green, and blue emission profiles. FIG. 7D depicts CIE 1931coordinates for the sum emission profile shown as the white trace in“FIG. 7C” along with the individual red, (x,y)=(0.61,0.34), green,(x,y)=(0.32,0.61), and blue, (x,y)=(0.16,0.07), coordinates.

Three chrome-coated glass photomasks were fabricated to containdifferent sized transparent rectangles for red (500×500 μm), green(125×750 μm), and blue (500×750 μm) pixels (masks 9, 10, and 11,respectively). The utility of larger rectangles than those used in anactual display is because of ease of sequential mask alignment, howeverresolution on the order of microns is achievable with this method, whichis competitive with state-of-the-art pixels for display applications(˜5×5 μm). A simple substrate holder composed of black Delrin andstainless still pins was built and used to align the masks (withapproximately ±100 μm accuracy).

Sequentially, poly(M6MA-co-IrbtpMA), poly(M6MA-co-IrppyMA), andpoly(M6MA) brushes were grown from ITO, providing red, green, and blueemissive rectangles, respectively (See FIG. 7A). Reflectance microscopyreveals that the pixels had a thickness of around 90 nm for red and 110nm for green and blue. FIG. 7B shows a photoluminescence microscopeimage of the sample under 365 nm excitation, demonstrating definedfeatures for the RGBG arrangement. The total photoluminescence outputfrom the array is measured in an integrating sphere (λ_(ex)=340 nm) todetermine the emission profile (FIG. 7C) and chromaticity (FIG. 7D).

A 395 nm long-pass filter is used to measure emission over the entirevisible spectrum (400-700 nm) without interference from the secondharmonic of λ_(ex), showing good overlay with individual emissionprofiles for red, green, and blue pixels that were measuredindependently. The chromaticity from the emission profile was generatedfollowing 1931 Commission Internationale de L'Éclairage (CIE)guidelines, identifying x,y coordinates of 0.35,0.32, which approachesnear pure white emission (x,y=0.33,0.33). FIG. 7D also shows theindividual CIE 1931 coordinates for red, (x,y)=(0.61,0.34), green,(x,y)=(0.32,0.61), and blue, (x,y)=(0.16,0.07), which exhibits theunderlying color mixing process that results in the “white” lightemission. The multicolored patterning demonstrates the ability for thismethodology to be used as an effective way to fabricate pixel arrays forOLED display applications.

Example 8

A monochromatic and multicolored OLED devices was fabricated using thepresent grafting-from procedure. FIG. 8A provides a schematicrepresentation of the multicolored device, with an architecture (frombottom up) of: ITO/EML/HBL/ETL/EIL/Al, where ITO is the anode, polymerbrushes comprise the EML,5-(4-([1,1′-biphenyl]-3-yl)-6-phenyl-1,3,5-triazin-2-yl)-7,7-diphenyl-5,7-dihydroindeno[2,1-b]carbazoleacts as the hole blocking layer (HBL, 5 nm),2,4-bis(9,9-dimethyl-9H-fluoren-2-yl)-6-(naphthalen-2-yl)-1,3,5-triazinecomprises the electron transport layer (ETL, 35 nm), 8-hydroxyquinolinato lithium (LiQ) the electron injection layer (EIL, 2 nm), andaluminum (Al) the cathode (100 nm). Two polymer brushes,poly(M6MA-co-IrpqMA), an orange emitter, and poly(M6MA-co-IrppyMA), agreen emitter, were grafted from six ITO pixels on one glass substrateusing low intensity 465 nm irradiation (0.4 mW/cm²) through twochrome-coated glass photomasks with three alternating transparentrectangles.

Based on reflectance color, the brushes were approximately 70 and 80 nmthick for poly(M6MA-co-IrpqMA) and poly(M6MA-co-IrppyMA), respectively.Applying forward bias on a fully fabricated device prototype led toobservable electroluminescence for all six pixels, and two distinctcolors (orange and green) as shown in FIG. 8B. Although deviceperformance will undoubtedly benefit from the incorporation of a holeinjection layer (HIL) and/or HTL between the ITO and EML, the potentialutility of this grafting-from platform for OLED display applications isclearly demonstrated by the ability to obtain a working multi-coloreddevice.

Example 9

This example is conducted to demonstrate photopatterned growth ofelectronically active polymer brushes for white organic light emittingdiode displays. The host monomer contains a carbazole-phenyl-pyrimidinemoiety covalently attached to methacrylate, termed M6MA, which wasconveniently prepared in four steps from commercial starting materials.Scheme 1 in the FIG. 10 provides the general synthetic strategy to thedesired heteroleptic and functional facial (fac) Ir (III) complexes toprepare the μ-dichloro bridged dimer [Ir(X)₂-μ-Cl]₂ (1) from IrCl₃.xH₂Oand one of four C^N ligands represented as X (vide infra), thensplitting of the chloro-bridge with silver triflate (AgOTf) and couplingwith 4-(pyridine-2-yl)benzaldehyde to yield compound 2. Aldehydereduction on compound 2 with sodium borohydride yields the correspondinghydroxymethyl derivative (compound 3), followed by acylation withmethacryloyl chloride to provide the desired iridium monomer, IrXMA,where the C^N ligand, X, dictates the triplet (T₁) energy and thusphosphorescence color. Specifically, X represents difluorophenylpyridine(dfppy), phenylpyridine (ppy), phenylquinoline (pq), orbenzothiophenylpyridine (btp) (Scheme 1). To confirm whether the IrXMAmonomers were compatible with M6MA under radical polymerizationconditions, linear copolymerizations were attempted by simply heatingthe two monomers (94:6 mol %, M6MA:IrXMA) in anisole in the presence ofazobisisobutyronitrile (AIBN). The polymerizations appeared to runsimilarly, independent of the IrXMA monomer, providing number averagemolecular weights (M_(n)) of 36±1 kDa and dispersities (Ð) of 2.4±0.1,relative to polystyrene standards. Additionally, the copolymers werefound to have unique emission profiles dictated by the IrXMA comonomer,granting access to turquoise (dfppy), green (ppy), orange (pq), and red(btp) colors, while homopolymers of M6MA provide deep blue fluorescence.

The precise control over emitter incorporation makes the generation ofwhite light possible through careful tuning of red, green, and blueemitting components using a random copolymer brush architecture. WhiteOLEDs are useful as a source of low energy backlighting for displaytechnology that achieves color by passing the light through a filter,such as a liquid crystalline display (LCD). White emission bycopolymerizing IrbtpMA and IrppyMA with M6MA to mix red and greenphosphorescence, respectively, while maintaining a low concentration ofeach, such that blue fluorescence from M6MA is not fully quenched by theemitters and can also be mixed in with the red and green.

A 1M solution of monomer in NMP (anh) was prepared inside of a glovebox,using M6MA, IrppyMA (0.2 mol % relative to M6MA), and IrbtpMA (0.25 mol% relative to M6MA). The mixture was added on top of an initiatorfunctionalized ITO substrate and a chrome coated glass photomask wasplaced onto the solution. The samples were irradiated with a collimated465 nm LED (0.4 mW/cm²) for 2 hours. The light was turned off and thesamples were removed from the glovebox, washed thoroughly with CH₂Cl₂,sonicated (1 minute) in CH₂Cl₂, and dried under a stream of nitrogen. Bycarefully tuning the feed ratio of the two IrXMA comonomers relative toM6MA, white emission is achieved with 0.2 mol % IrppyMA and 0.25 mol %IrbtpMA.

What is claimed is:
 1. A device comprising: a substrate; where thesubstrate comprises a plurality of brush polymers that are covalently orionically bonded to the substrate; where at least a portion of the brushpolymers comprise a covalently bonded emitter moiety; where the brushpolymers comprise a polymeric chain backbone that has an electroactivemoiety extending radially outward from the chain backbone; and where theelectroactive moiety is linked to the chain backbone by a covalent bond,an ionic bond or a hydrogen bond.
 2. The device of claim 1, where thesubstrate comprises a first region comprising a first brush polymer anda second region comprising a second brush polymer; where the first brushpolymer and the second brush polymer are covalently or ionically bondedto the substrate; where the first brush polymer comprises repeat unitsof a first ethylenically unsaturated monomer and a second ethylenicallyunsaturated monomer; where the first ethylenically unsaturated monomercomprises a first electroactive moiety and where the secondethylenically unsaturated monomer comprises a second electroactivemoiety that is different from the first electroactive moiety; where atleast one of the first electroactive moiety or the second electroactivemoiety is an emitter moiety.
 3. The device of claim 2, where thesubstrate further comprises a third region that comprises a third brushpolymer disposed on the substrate; where the third brush polymercomprises repeat units of the first ethylenically unsaturated monomerand/or the second ethylenically unsaturated monomer; where the firstethylenically unsaturated monomer comprises a fifth electroactive moietyand where the second ethylenically unsaturated monomer comprises a sixthelectroactive moiety.
 4. The device of claim 3, where the first region,the second region and the third region are separated from each other andwhere the first electroactive moiety, the second electroactive moiety,the third electroactive moiety, the fourth electroactive moiety, thefifth electroactive moiety and the sixth electroactive moiety arechemically different from each other and are at least one selected froma host moiety, a hole transport layer moiety, a hole injection layermoiety, an emitter moiety or an electron transport layer moiety.
 5. Thedevice of claim 1, where the plurality of brush polymers form anemissive layer that emits fluorescent light and/or phosphorescent light.6. The device of claim 5, where the plurality of brush polymers furtherform at least one of a host emission layer, a hole transport layer, ahole injection layer and/or an electron transport layer in addition tothe emissive layer; and where at least one of the host emission layer, ahole transport layer, a hole injection layer and/or an electrontransport layer contact the emissive layer.
 7. The device of claim 6,further comprising an anode and a cathode; and where the device is anelectroemissive device.
 8. The device of claim 7, wherein the saiddevice comprises a display that comprises light emitting pixels that areactivated to display individual colors or color combinations.
 9. Thedevice of claim 8, wherein the device is a light source that emits lightof a single color or of a plurality of colors.
 10. The device of claim9, wherein the device emits white light.
 11. The device of claim 9,where the emitted light is transmitted through a color conversion layer.12. The device of claim 11 wherein the color conversion layer comprisesa multiplicity of pixels of a multiplicity of colors.
 13. The device ofclaim 3, where the first region, the second region and the third regioneach produce light of different wavelengths respectively.
 14. The deviceof claim 1, where the device is a light emitting diode.
 15. The deviceof claim 1, where the device is a white organic light emitting diode.